Cognitive impairments that clinically resemble dementia are frequently observed in elderly schizophrenic patients. The study proposed in this application will investigate if the "dementia" observed in these elderly schizophrenic patients share the same neurohistological substrates as in known dementing illnesses like Senile Dementia of the Alzheimer's Type or Multi Infarct Dementia. Such a finding would indicate that observed cognitive deficits may be independent of the schizophrenia and reflect the concurrent presence of another dementing illness. Alternatively, brains derived from cognitively and functionally impaired elderly schizophrenic patients will not meet neuropathological criteria for known dementing illnesses. Such a finding would strongly suggest that elderly schizophrenic patients with cognitive dysfunction are affected by a clinical condition which resembles other recognizable dementing illnesses (Senile Dementia of Alzheimer's Type, Multi Infarct Dementia), but without the corresponding neuropathological correlates characteristic of these dementias. This potential outcome would further suggest that the severe cognitive and functional impairment observed in some elderly patients is another aspect of the schizophrenic illness, and not a concomitant known dementing illness. In order to achieve these aims, detailed cognitive and functional assessments will be conducted antemortem in patients who are older than 65 years and who meet DSMIII-R criteria for schizophrenia. These patients will be followed until death at which time the brain will be expeditiously removed and neurohistologically assessed. This study will be conducted as a collaboration between the Department of Psychiatry and Neuropathology at Mount Sinai School of Medicine and the New York State Pilgrim Psychiatric Center.